This invention relates to assembly tools. More specifically this invention relates to automatic screwdriver equipment and component elements thereof.
Automatic screwdrivers of the type disclosed in this application are screwdrivers which are power operated and best suited for use in product assembly work.
Typical of the applications of such automatic screwdrivers is an assembly line operation wherein the assembled product includes a screw which has been partially or totally threaded into a suitable bore in the product. Where the product incorporates more than a single screw in its final assembly, more than one automatic screwdriver may be utilized in the assembly line. Typical of the products incorporating such partially threaded screws is the electrical receptacle which, in its consumer-available form, usually has box-attaching screws attached thereto.
Automatic screwdriver apparatus are known in the industry. Typical of the apparatus presently known and used is that shown in U.S. Pat. No. 2,989,996 for POWER OPERATED MECHANISM FOR ASSEMBLING THREADED FASTENERS.
The present invention also relates to a ball clutch apparatus appropriate for use in power equipment such as the screw driver of the present invention. Ball type clutches are known in the industry. Typical of the ball clutches presently known are those shown in U.S. Pat. Nos. 3,168,944, 3,693,381 and 3,726,432, which patents are submitted to be representative of the State of the art.
As will be recognized by those skilled in the art, however, certain operational disadvantages are present in the known automatic screwdriver structures which adversely affect their operation. Thus, known automatic screwdriver apparatus do not incorporate structure for positively limiting the degree of advance of the screw into a bore and physically terminating the rotation of the screwdriver bit at a point of total advancement. Further, known apparatus have not incorporated positive engagement clutch means capable of disengagement upon the completion of screw advance and positive re-engagement upon commencement of a next subsequent screwdriving cycle.
Additionally known ball type clutches suffer from a lack of positive lock-out during the disengagement phase of their operation. Such lack of lock-out results in unacceptable chatter and fatigue in the clutch which is both undesirable and damaging.